Re: [Qemu-devel] [Qemu-stable] [PATCH v2 1/1] block/vmdk: Fix the endian problem of buf_len and lba

[Fam Zheng <famz@redhat.com>]

On Sat, 11/26 06:46, QingFeng Hao wrote:
> The problem was triggered by qemu-iotests case 055. It failed when it
> was comparing the compressed vmdk image with original test.img.
> 
> The cause is that buf_len in vmdk_write_extent wasn't converted to
> little-endian before it was stored to disk. But later vmdk_read_extent
> read it and converted it from little-endian to cpu endian.
> If the cpu is big-endian like s390, the problem will happen and
> the data length read by vmdk_read_extent will become invalid!
> The fix is to add the conversion in vmdk_write_extent, meanwhile,
> repair the endianness problem of lba field which shall also be converted
> to little-endian before storing to disk.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
> Signed-off-by: Jing Liu <liujbjl@linux.vnet.ibm.com>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/vmdk.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index a11c27a..26e5f95 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1354,8 +1354,8 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
>              goto out;
>          }
>  
> -        data->lba = offset >> BDRV_SECTOR_BITS;
> -        data->size = buf_len;
> +        data->lba = cpu_to_le64(offset >> BDRV_SECTOR_BITS);
> +        data->size = cpu_to_le32(buf_len);
>  
>          n_bytes = buf_len + sizeof(VmdkGrainMarker);
>          iov = (struct iovec) {
> -- 
> 2.8.4
> 
> 

Reviewed-by: Fam Zheng <famz@redhat.com>